The platinum (Pt) nanoparticles were synthesized by laser ablation of Pt target in distilled water. In addition, the
UV-vis absorption spectrum and nonlinear optical properties of these NPs, exposed to the 532 nm laser beam, have been
investigated using Z-scan method. The results indicated the saturable absorption behavior of Pt NPs in lower laser intensities.
This behavior was switched to the reverse saturation of absorption in higher laser intensities. In addition, the nonlinear
refractive index has negative value and was increased with increasing of laser intensity.